Safety thermal circuit breaker



June 1, 1948. A. F. JACKSON 2,442,693

SAFETY THERMAL CIRCUIT-BREAKER f I :nllllllllllll fllllllllllllllllINVENTOR ATTORNEYS Agfrea? [Jew/i190, I

Patented June 1, 1948 SAFETY THERMAL CIRCUIT BREAKER Alfred F. Jackson,Bridgeport, Conn assignor to Automatic Devices Corporation, Bridgeport,Coma, a corporation of Connecticut Application November 11, 1943, sci-n1No. 509,829

'2 Claims. (01. 2oo 1as) This invention relates to cigar lighters andmore particularly to an automatic cigar lighter having an improvedsafety device.

In some instances, cigar lighters have been destroyed by overheating ofthe igniting unit caused by a short-circuit or other functional defect,or by inadvertently maintaining the cigar lighter in energizing positionby manual or other pressure, for instance, by resting the foldable frontseat of a vehicle against the knob of the cigar lighter.

An object of the present invention is to provide an inexpensive, easilymanufactured device to be attached to an automatic cigar lighter whichwill permanently open the circuit if the heating element of the cigarlighter should attain some dangerous heat from any cause, and whichdevice is not self-destructive upon operating but may be reconditionedfor use by manual operation. The device preferably has means whereby thebreak in the circuit to the heating element of the cigar lighter may besensually ascertained without disassembling the device and by whichmeans the circuit may be manually reset when the cause for thisoverheating has been removed. This has been accomplished, according tothe present invention in the form at present preferred, by attaching tothe holding device of an automatic cigar lighter a safety device whichforms a part of the circuit of the heating element and includes abimetallic circuit-carrying switch so located in heat-receiving relationto the holding device and igniting element that should the latter attaina dangerous heat, the action of the bimetallic element results in thecircuit being opened and remaining open until the switch is again closedby a deliberate manual operation.

In the specific form of the invention illustrated herein as exemplarythereof, the device comprises a body attached to the rear of the holdingdevice and having slidable in apertured walls thereof a block havingresilient means urging it outwardly.

The block is maintained in inoperative position against the action ofthe resilient means by the circuit-carrying bimetallic strip. Uponoverheating, the excessive heat transmitted to the bimetallic stripcauses the latter to deflect and breaks the circuit, releasing thesliding block for movement by the resilient means to a position in whichthe bimetallic strip is prevented from again closing the circuit. Thisalso causes a button on the block to project from the body and thisindicates that the circuit has been broken by the safety device. Uponremoval of the cause for overheating and consequent cooling by atransverse wall iii of the socket l0.

2 of the bimetallic strip, the latter tends to return to its normalcontacting position but is restrained by the extended block. By simplyurging the said block back into the bearing, the strip is allowed toreestablish the circuit and again maintain the sliding block in itsinoperative position.

Other features and advantages will hereinafter appear.

In the accompanying drawing which illustrates one form of thisinvention, that at present preferred- Figure 1 is a longitudinalsectional view of an automatic cigar lighter showing the device of thisinvention attached thereto.

Fig. 2 is a longitudinal sectional view showing the heat-responsiveelement in its normal closedcircuit position.

Fig. 3 is a similar view showing the various elements of the deviceassembly in open-circuit position.

.Fig. 4 is a longitudinal sectional view taken along lines l4 of Fig. 2,showing the parts in closed-circuit position.

Fig. 5 is a similar view taken along lines 5-5 of Fig. 3, showing theparts in open-circuit position.

Fig. 6 is a transverse sectional view taken along lines G--6 of Fig. 5.

Fig. '7 is a section of the rear end of the cigar lighter showing amodified form of securing means.

In the particular lighter illustrated in Fig. i, the holding devicecomprises a well or socket iii adapted to be mounted in an aperture inan instrument board H of an automobile or the like with a flange !2 ofthe socket in engagement with the front face of the instrument board.The well is secured in place by a tubular shell l3 having a nipple l4threaded over a boss i5 carried The igniting unit Il may be a generallycylindrical member having a sliding seat within the cylindrical shellit.

In the form of the invention as herein shown, the igniting unitcomprises a body portion and a knob member ill. The inner end of theigniting unit is provided with a heating element ill. The igniting unitis adapted to be held in shallow open-circuit position by resilientmeans housed in the sleeve 20, the outer end of which engages the flangel2 of the holding device.

To complete a circuit to the heating element, the igniting unit is movedto a deep position in the holding device, causing the cup of the heatingelement 19 to engage live contact fingers 2i and V r thus cause theheating element to'glow. The fingers 2| are made of resilient bimetaland are shaped as detents or latches, so that they grip and retain theigniting unit against return movement until-the heating element has beenbroughtto a predetermined temperature for use.

when the heating element has reached the desired temperature, the heattherefrom is conducted to the fingers 2| causing them to flex andrelease the igniting unit IT for return to the shallow inoperativeposition, breaking the circuit to the heating element. The igniting unitmay then be removed and used.

Due to abuse, such as excessive improper use or natural fatigue of partsafter having been used over a long period of time, there is apossibility that the fingers 2| will fail to flex. If such a failureshould occur, the heating element would reach a dangerous heat, whichcan cause the destruction of theentire device. Such a dangerous heatmight'also be attained if the unit were 4' responsive switch, preferablyin the form of a bimetallic switch arm 35. One end of the switch 33 issecured to the bushing 25 while the other end 31 due to the shape andresiliency of the switch arm normally engages the contact disk 34.

When the cigar lighter becomes overheated, heat is conducted through thebushing 25 to the switch arm 35 and because of its bimetallic or Ithermostatic construction, the latter is bent or flexed so as to raisethe end 31 thereof of! the disk 34 to open the circuit. Thisinterruption of 'the circuit'would immediately deenergize the latter andthus prevent continued overheating,

- which would be dangerous, for the bimetallic before the conditioncausing the overheating were inadvertently ,held in energizing positionby manual or other pressure, such as pressure provided by the resting ofthe folding front seat of the vehicle against the knob It. To preventdestruction of the entire device by overheating, should the bimetallicfingers 2| fail to respond properly and release the igniting unit. orfor any other reason, the present invention provides a means which willpermanently open the circuit should the cigar lighter become overheated,and

yet which will not be destroyed after one opera- 7 tion but may berepeatedly used indefinitely.

The invention also provides means by which breaking of the circuitby theimproved means may be sensually ascertained and for manually tactassembly in the socket it.

The assembly comprises a housing or body-23 preferably made of -moldedinsulating material,

having an end 24 provided with an aperture carrying a threaded sleeve orbushing 25 spun over a washer 26 on the outside of the body. As shown inFig. 1, this sleeve 25 is threaded on the stud 22 so that it engages theinsulating washer 28 and thus holds the, contact assembly, including thebimetal fingers 2| securely in position in the end wall of the socket|0.-

At the other end of the body 23 and spaced from the end of the sleeve 25there is a plug 21 having screw threads 23 engaging a threaded hole 23in the body. The plug 21 has a threaded stud 30 which carries a nut 3|by means of which the plug is tightened in the body and which receives aterminal lug of a current-supplied wire 32 and a binding nut 33. Withinthe body, the plug 21 has a contact disk 34 forming one side of the gapin the circuit which is automatically controlled according to thepresent invention. The other side of the gap is formed by the bushing25, which as above pointed out. Solong as this gap is open, no currentcan flowfrom the supply wire 32 to the contact flngers zl.

To automatically control this gap in the circuit so that it remainsclosed so long the the cigar lighter is functioning properly, thepresent in ventionprovides within the housing 23 a heatremoved orcorrected, it would continue opening I and closing indefinitely, thuspermitting unnecessarydraining of the battery.

According to the present invention in its preferred form, however, theautomatic reclosing of the circuit by the switch 35 is prevented until adeliberate and intentional manual operation has been performed, therebyavoiding draining of the battery and calling the'users attention to thefact that the device has not functioned properly.

To accomplish this, the present invention pro- 7 vides within thehousing an automatically set ment of the pin.

is electrically connected to the contact fingers2l,

andmanually reset lock-out device for blocking return of the switch arm35 to circuit-closing position after the circuit has been openedthereby. As shown in the accompanying drawing, this lock-out devicecomprises a pin 38, one end of which has a sliding mounting in one sideof the housing and the other end of which projects through a hole in theother side of the housing.

The pin 38 extends across the space between the contact disk 34 and thebushing 25 and adjacent the path of the switch arm 35 which is" bentsubstantially Z-shaped The pin 38 is normally urged outwardly of thebody 23 by a spring 33, and the pin has an en-' largement 40 whichnormally engages a portion 4| of the switch and limits the outward move-In the form of the invention herein shown as exemplary thereof, theenlargement 40 is in the form of a frustum of a cone so that it willoperate in all angular positions of the pin in the body.

and the pin is set at an angle in the body so that the surface of thefrustoconicalenlargement 40 adjacent the portion 4| of the switch 35 isparal-' lel to that portion of the switch. 2

When the switch arm 35 is-in circuit-closing position as shown in Figs.2 and 4, the engage-V ment of the enlargement 40 with the switch armprevents outward movement of the pin 33 because the spring 33 isnotstrong enough to overcome the resiliency of the switch arm 35. When.however, the switcharmflexes upon the cigar lighter being overheated;the portion 31 of the switch arm moves to the right as shown in Figs. 2and 4, and this permits the pin 33 to advance under the influence ofspring 39 and take up a position under the portion 4| of the switch armas shown in Figs. 3 and 5. In this position, the frustoconical wedge orobstruction 43 on the'pin 33 blocks the return of the bimetallic switcharm -trips or latches, the slight wearing of which might affect thesuccessful operation of the device.

With the frustoconical obstruction 40, the pin begins to move under theportion 4| of the switch arm 35 as soon as the switch arm moves evenslightly, and the amount of movement which the pin 38 and itsobstruction 4| may have depends upon how far the contacting end 37 ofthe switch arm moves away from the contact disk 34; in other words, theamount of overheating. This is so because there are no limiting stopsfor the pin and its obstruction other than the switch arm itself.

Another advantage of the blocking device 38 of the present invention isthat the enlarged end of the frustoconical locking member 40 need not beany larger than the outer end of the pin 38. Therefore, the pin 38 maybe assembled by merely projecting it longitudinally through its mountingholes 42 in the body 23.

As stated above, another feature of this invention is the provision ofmeans for sensually indicating that the circuit has been opened by thesafety device. This is accomplished by causing the end of the pin 43 toproject sufliciently beyond the body 23 when the switch arm 35 has movedto open-circuit position, such, for instance, as shown in Figs. 3 and 5,to indicate either by observation or by feeling whether or not it hasbeen projected.

After the cigar lighter has become overheated and the fault ordiiliculty has been obviated, it is merely necessary for the user or themechanic making the repair to push inwardly on the'button-like end 43 ofthe pin 38 so as to restore it to its Figs. 2 and 4 position. It is notnecessary to disassemble the safety device or make any mechanical orelectrical adjustmentsit is merely necessary to restore the pin.

As shown in Fig. 1, the device'oi the present invention constitutes themeans for holding the stud 22 and contact finger assembly, in-the wellof the cigar lighter, and thus the device can be removed withoutdangerof the cigar lighter becoming disassembled. If it should bedesired to attach the device to an existing cigar lighter or to make itso that it may be attached or removed, it is merely necessary to place alocking nut 44 on the end or the stud 22 to secure the contact assemblyin place before the housing is screwed onto the end 01 the stud.

Variations and modifications may be made within the scope or thisinvention and portions of the ducting means disposed in one end of thehousing forming a connecting means; conducting means mounted in theother end of the housing for connection to a source of electricalenergy; a bimetallic strip in the housing normally maintaining acircuit-closing position between both said conducting means; and a wedgeslidabl carried by said housing being engaged and maintained ininoperative position by said bimetallic strip in closed-circuitposition, said bimetallic strip flexing and moving in response to a'predetermined heat to break the circuit at the initiation of itsmovement, said wedge being released and moving to a position in which aportion of the wedge projects from the housing, and the enlarged portionof the wedge engages said bimetallic strip and prevents the strip fromreturning to closedcircuit position, the projecting portion of saidwedge being manually moved into the housing whereby said bimetallicstrip may return to circuit-closing position.

2. A safety device comprising a housing having apertured walls formingbearings; conductin means disposed in one end of the housing forming aconnection means; conducting means mounted in the other end of thehousing for connection to a source of electrical energy; a bimetallicstrip in the housing normally connecting both said conducting means; awedge-type blocking member having a button slidably carried by saidbearings, resilient means for urging the blocking member outwardly, saidblocking member being maintained in inoperative position against theaction of the resilient means by said bimetallic strip when inclosed-circuit position, said bimetallic strip flexing and moving inresponse to a predetermined heat to break the circuit at the initiationof its movement and release said blocking member for gradual movement ascontrolled by the flexing of the strip to a position in which the buttonon said blocking member projects from said bearings, said blockingmember engaging the bimetallic member in open-circuit position and beingprevented thereby from further movement and said bimetallic strip beingprevented from returning to circuit-clos n P tion by the blockingmember, the projecting button upon being moved within said aperturedwall causing the blocking member to release the bimetallic strip forreturn to normal circuit-closed position wherein said bimetallic stripagain maintains the blocking member in inoperative position against theaction of the resilient means.

, ALFRED F. JACKSON.

nnrnnnncns crrnn The following references are of record in the file ofthis patentz- UNITED STATES PATENTS Cohen Aug. 10, 1943

